Measurement and shaping of biphoton spectral wavefunctions

TL;DR

This paper introduces a straightforward quantum interference-based method to reconstruct and shape the spectral wavefunction of biphotons, enabling detailed control over their spectral and temporal properties.

Contribution

It presents a novel technique for complete biphoton spectral wavefunction reconstruction using quantum interference, applicable to SPDC sources with spatial mode control.

Findings

Successful reconstruction of biphoton spectral wavefunctions.

Demonstration of spectral wavefunction shaping via spatial mode selection.

Potential for enhanced control of photon pair properties.

Abstract

In this work we present a simple method to reconstruct the complex spectral wavefunction of a biphoton, and hence gain complete information about the spectral and temporal properties of a photon pair. The technique, which relies on quantum interference, is applicable to biphoton states produced with a monochromatic pump when a shift of the pump frequency produces a shift in the relative frequencies contributing to the biphoton. We demonstrate an example of such a situation in type-II parametric down-conversion (SPDC) allowing arbitrary paraxial spatial pump and detection modes. Moreover, our test cases demonstrate the possibility to shape the spectral wavefunction. This is achieved by choosing the spatial mode of the pump and of the detection modes, and takes advantage of spatiotemporal correlations.